1. Field of the Invention
This invention relates to an X-ray generating method and an X-ray generating apparatus, which are particularly usable for medical treatment.
2. Description of the Background Art
In X-ray photography for medical use, a given X-ray tube is employed, and an X-ray is irradiated onto an object from the X-ray tube so that the X-ray through the object is photographed and detected at a detecting section such as an X-ray sensitivity film, and the thus obtained image is analyzed for the medical use.
For example, an X-ray generated from a conventional X-ray tube has an effective focal spot with 1 mm×1 mm. When the irradiated surface area on the object is 10 cm×10 cm, it is necessary to enlarge the x-ray size to 10 cm×10 cm. In this case, the brightness of the X-ray is weakened by a ratio of (1 mm×1 mm)/(100 mm×100 mm). In other words, when the conventional X-ray tube is employed, the brightness of the X-ray is decreased to 10−4 times as the initial brightness of the X-ray from the X-ray tube.
Moreover, in the medical use of the conventional X-ray tube, some components with unnecessary wavelength would be cut off with some filters. Thus the unnecessary components can not be removed sufficiently.
In order to photograph a moving object such as coronary artery in the medical use at high resolution, it is required to irradiate a high intensity X-ray with excellent parallelism and high power onto the moving object in a short period of time. In the conventional X-ray tube, however, the brightness of the X-ray is remarkably decreased when the X-ray is irradiated onto the moving object and the parallelism of the X-ray can not be realized sufficiently. In this point of view, the medical use of the conventional X-ray tube is restricted and thus, can not be employed for wide medical use.